Pot-type oil burner



July 21,. 1953 w. o. HORNE POT-TYPE on. BURNER Filed Oct. 9; 1947 Ill/LIA; HORNE-3mm! '6. 5. JW/

(Ittorneg Patented July 21, 1953 UNITED STATES ATENT OFFICE 7 Claims.

1 Thisinvention relates type. The quality of fuel oils available for vapor"- izingpot-type burners has deteriorated during recent years. Gravity and diesel points have been lowered and end points and carbon residue'st'have increased. Ihis unfavorable situation is further aggravated by the growing economic necessity for using increased amounts of cracked fuels for domestic heating. Straight-run distil lates of high quality are increasingly scarce and expensive.

One characteristic of the heavier fuels available for vaporizing burners is that, as the gravity lowers, the range between the dew point temperature and the cracking point temperature is narrowed. Where this range is considerable for straight-run distilled kerosene-possibly 156 F. -it becomes decreasingly less with heavier fuels until, with some catalytically cracked fractions, the range may approach zero degrees or even have ,a cracking point temperature below its dew point temperature.

A further property of these heavier fuels and one that makes their use difficult in vaporizing type. burners, particularly of the natural draft type, is the smaller percentage of hydrogen in these fuels. For the ratio of hydrogen to carbon in fuel oil decreases as the oil becomes heavier. It is well established that the tendency of a hydrocarbon to smoke while burning is in direct proportion to the humidity of the products of combustion. The decreased amounts of hydrogen, therefore, in these heavier fuels, becomes a problem of clean combustion if they are to be successfully used in this type of burner.v

The primary object of the present invention, therefore, is to provide a fuel vaporizing burner of the pot-type that will accept some of these heavier available fuels and burn them with high efiiciency, with less resulting smoke and carbon, and at lower chimney drafts.

Afurther object of the invention is toprovide a burner, as indicated, that will completely vaporize the fuel oil used without decomposing or cracking the same.

. A further object is to provide means for intro ducing water vapor into a pot-type burner so as to increase the ratio of hydrogen to carbon in the fuel gases generated therein.

Afurther object of the invention is to provide a pot-type burner wherein the largest possible proportion of vaporized gases, during both primary and secondary oxidation, is exposed to air introduced according to the reverse flame principle.

Corollary objects of to oil burners of the potvidea pot-type burner embodying means for obtaming an all blue low or pilot fire; to obtain a blue base to any fire above the low fire and within the capacity of the burner; to completely segregate and shield the vaporizing surface and the initial aeration area of the burner from direct radiation of the flame above at all flame levels; to limit the vaporizing temperature on the burner bottom to a temperature only slightly above the dew point of the fuel; to apply this heat, as far as possible, to the bottom of the burner instead of to the surface of the fuel; and to make the lighting of the burner simpler, safer and cleaner.

Specifically, one novel feature of my invention is the provision of a grid or shielding member generally of plate-like construction interposed between the top and bottom of the burner pot above the lowermost primary air holes to shield the infiowing fuel oil from direct radiant heat when the flame is above such member and to divert the gases outwardly from beneath such member toward the side wall of the burner pot; also to provide apertures in the side wall of the pot of such contour and form as to provide for efficiency in the flow of air therethrough into the interior of the pot by increasing the velocity and thereby the Volume of air flowing through such apertures, and the penetration of the air jets into thepot. r

Another object is to shield the oil inlet against direct radiation from any flame so that at low fuel supply the inflowing oil will be so shielded to prevent cracking and formation of carbon or sticky residue by the provision ofwhat I term a pilot plate which while so shielding the oil delivered will not impair the required supply.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely. describes embodiments of the present invention, which are given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. 1 is a vertical sectional view of a pot-type burner constructed in accordance with the present invention.

Fig. 2 is a fragmentary cross-sectional view of a modified grid employed in the burner.

Figs. 3, 4 and 5 are greatly enlarged fragmens tary sectional views through the wall of the burner, showing various forms of air-admitting orifices or ports.

Fig.6 is a fragmentary cross-sectional view of an alternate form of pilot plate employed in the burner.

The burner which is illustrated comprises, generally, a pot It having an open top, a choke ring if or baffle partially closing said top, a'grid or plate l2 across the interior of the pot intermediate its top and bottom to define a vaporizing and initial aeration area it therebelow, and a primary and secondary aeration space M thereabove, a fuel inlet [5 to the bottom of the pot, a pilot plate (6 loosely resting on the pot bottom across said inlet, means ll for admitting water vapor to the upper area of the burner, means comprising ori-' fices t8 and I9 for introducing jetsof air into chambers l3 and 14, respectively, and an opentopped annular ring 2%] for shielding and regulating the temperature of the lower air admitted to the burner.

The pot It has a bottom 2| with a cylindrical side wall 22. Means, such as pins 23, are provided intermediate the height of wall 22 to form a support for grid E2. The open top of the pot is shown with an outwardly directed annular flange 24 serving to secure and support choke ring i I. The latter has a cross-sectional form 25 that is inwardly and'downwardly curved for increasing the turbulence of the air-gas mixture in the upper chamber or area Id.

The pot bottom 2! has a central opening 26 for the fuel inlet [5. The latter comprises a T-fitting 2'! having a laterally directed port 28 for connection to a fuel line, an upper'port 29 for passing fuel into the pot, and a lower threaded opening 30 for a water line 3!.

The grid l2, shown in Fig. 1, comprises a generally flat metal plate 32 that loosely fits within the pot wall 22 and removably rests on pins 23. Said plate 32 is formed with a multiplicity of louvered openings 33 which effect communication between areas If! and M. Said louvered openings are so formed that such communication is not direct but rather obliquely indirect.

The grid l2 may be variously formed to attain the mentioned indirect communication between areas It and Hi. As shown inFig. 2, a series of progressively larger metal rings 34 and 35 having a central concentric metal plate 36 and suitably overlappingly spaced to form annular communicating spaces 31, may serve as an alternate for the grid shown in Fig. 1. parted to said rings and plate by providing upturned and/or downturned flanges 38 thereon.

The above-described grids should be made of a chrome-nickel alloy or of porcelain-coated steel to reduce oxidation and unfavorable catalytic action on heated and partly aerated gases coming in contact therewith.

The pilot plate it comprises an element of porous material placed loosely over fuel inlet port 29 and sufiiciently large to completely cover the low fire pool of fuel during low fire operation. The material of the pilot plate is of a lavaor pumice-like nature, and is highly heat resistant, strong and porous for the present purpose. As shown in Fig. 6, said plate may be provided with a multiplicity of teats or projections 46 that rest on the pot bottom.

The water vapor admitting means I! comprises a tube ll extending from water line 3| into the interior of the pot and through suitable openings provided in pilot plate l6 and grid l2. Said tube terminates in area l4 and in its upper portion carries a loosely packed material 48 that is not aifected by heat or water. Its purpose is to allow water vapor to escape into area [4, but prevent Strength may be imraw water from boiling over the top. It allows water to be introduced into the burner only in the form of steam. The height of the water 49 in the tube may be controlled by an external constant level device to regulate the amount of water evaporated into the burner, and/or a regulating valve can be added to control the amount of water in relation to the oil flow.

In order to preserve the blue or aldehydous character of the low fire and the high fire base, both of which are essential to freedom from carbon and soot deposits within the burner, vaporization of the fuel and the initial aeration of these vapors should be accomplished at relatively low temperatures. This is doubly important and increasingly difficult with the heavier fuels as already pointed out. The most efiicient vaporizing temperatures are at, or slightly above, the dew point of the fuel. This is a lower temperature than is commonly employed for this purpose. Actually, it is lower than the distillation end point of the fuel. But the amount of radiant heat reflected on the vaporizing area is a variable. During high fire operation, the flame is high in the burner and the radiant heat on the bottom consequently is low. As the fuel flow is decreased, the flame lowers in the burner, increasing the radiant heat on the bottom. "The grid l2, interposed between the radiant flame front and the vaporizing area, cuts off all direct radiation from the flame front and lowers the vaporizing temperature sufficiently to permit an aldehydous or blue flame sequence of combustion reactions at all flame levels. On the very lowest fires the bottom temperature is still high 'and the pilot plate is added for further protection.

The air orifices i8 and [9 in the pot wall 22 supply air for combustion of the heated gases. Preferably, the metal around each opening is extruded inwardly as in Fig. 4 about the thickness of the wall, while the outside approach is well rounded and smooth to thereby greatly increase the speed and energy of the incoming air. Suggested variations of these orifices within the scope and spirit of this invention are shown in Figs. 3 and 5.

Both the open-topped annular ring 28 and the down-curved choke ring I l are optional but desirable, and the advantages of both are set forth in my patent entitled Pot-Type Burner, No. 2,264,378, dated December 2, 1941.

The above-described burner is designed to be lighted through the lighter opening 52, and without need for access to the combustion chamber above the burner. Suflicient oil is admitted through inlet I5 to cover an area on pot bottom 2| under the pilot plate It. The latter also acts as a temporary wick and is ignited by a conventional asbestos-wire lighter. The open tube provides extra air for rapid generation of the fuel vapors until the excess fuel has been burned, whereupon if the fuel flow is already limited to approximately one-tenth of the high flow, closure of the lighter tube will provide a completely blue flame that is entirely below the grid or above the grid, depending on the size of the low fire adjustment and the type of grid used.

If the fuel supply be reduced to the point where the resultant blue pilot flame is below or partially below the grid I2, the pilot plate 56 will function to shield the inflowing oil from any radiant heat resulting from such pilot flame below the grid [2. If a pilot flame is arranged for, entirely above the grid l2, the pilot plate It may be omitted.

, sents some problems.

As the fuel flow is increased, the area of the filmof fuel on the bottom 2! increases, until at full'fire it covers most or allofthe burner bottom. The visible flame lifts as the fire is increased, until at high fire it is almost entirely' above and outside the burner pot ill. The lower part, of this radiant flame is streaked with blue while the base is entirely blue and the balance ofthe areabeneath (one-half or more of the entire burner volume) is completely free of an visible na e." This area includes considerable space'above the grid [2, as well as below'it. Within this flame-freearea initial aeration and; mixture of all vaporized gases is speed ;and.penetrative force of thesev jets Varies greatly. The coefiicient of dischargef the sharp-edge hole commonly used,.at bestis about .6 that of free air, and it may be'.5 or even .4. The orifice lfi according to this invention, has a co-efficientof .9 plus. Theenergy of the jets varies,-with, the square of, their co-eflicients. The penetrative length into the gas atmosphere,

' therefore, of these air jets ismore than doubled, Q resulting in increased aeration and better mixing of the'gasesg In the upper combustion area of the burner, these lengthened jets of air enlarge the peripheral surface of the jet and thus'increase the amount of gasesexposed to reverse fiarnecombustion. The latter is a stream of, air burning in an atmosphere of gas and produces a clean blue aldehydous-type of combustion in contradistinction' to a jet 'of gas burning in air. These jets are finally combined and dissipated in the area above the burner and the flame therein becomes radiant;

The use ofwater vapor and the principles underlying its" use toassist the combustion'of liquid fuels is'well knownl Its effective appli cation and regulation for pot-type burners, pre- In my invention, the vaporizing heat of the burner flame creates steam in tube 41 that enters area M where it mingles with the oil-gas vapors and is carried up into the luminous flame area above the burner where suflicient heat is present to effect dissociation of the H20 molecule. It is my belief from observation that the particles of luminous carbon act as catalysts to effect this dissociation and to lib-r erate free hydrogen and oxygen to function as stated, since the temperature of the flame I believe to be below the point of thermolysis of water vapor or steam. The released oxygen combines promptly with the luminous carbon particles to produce carbon monoxide a water gas reaction. ,Whether, and how often, the released hydrogen oxidizes and repeats this reaction, is not known, but the visual and the easily measured effects are startling. Badly smoking flames and hazy combustion chambers become clear and clean; CO2 readings are increased; and necessary stack drafts reduced. While it would seem that the amount of steam to be added could logically and economically be limited to an amount necessary to restore the hydrogen content of the fuel to kerosene equivalency, a ratio of 5% to of water to fuel has'been found practicable and even higher amounts may be indicated. In some applications, side ejection of ,the steam from the tube 41 may be indicated because the humidification of the gases within the burner area has been found to discourage cracking of the fuel and the deposit of carbon and coke on the burner walls. Proper humidification of the fuel and combustion chamber significantly increases the heat transfer qualities of both the flame and the non-luminous gases of the products of combustion. However, the moisture supply means may be omitted and satisfactory operation of the burner still obtained. The combination of the water vapor with the grid, the'formed orifices, and pilot plateQproduces a clean efiicient fire from low grade fuels at low drafts. 5

While I have illustrated and described what I now regard as the preferred embodiments of my invention, the constructions are, of course,

' subject to modifications without departing from the spirit and scope of my invention.

I, therefore, do'not wish to restrict myselfto the Darticular forms of construction illustrated and described, but desire to avail myself of. all modifications'that may fall within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: 1. An oil burner comprising a pot having a bottom and-a side-wall, such sidewall being provided with air holes at different levels, a grid member positioned in said pot above some of said air holes and below others of said holes and extending transversely of said pot, said gridbeat the bottom of said pot.

2. An'oil burner comprising a pot having a bottom and a side wall, such side wall being provided with air holes at different levels, a grid member positioned in said pot above some of said air holes and below others of said holes and extending transversely of said pot, said grid being provided with apertures and shieldin means overlying the same, said shielding means comprising portions of said grid bent upwardly and outwardly in such manner as to shield the underlying fuel oil in said pot from radiant heat and to direct substantially all of the gases vaporized in the bottom portion of the pot from beneath said grid outwardly toward the side wall of said pot, and means to supply oil at the bottom of said pot.

3. An oil burner comprising a pot having a bottom and a side wall, such side wall being provided with air holes at difierent levels, a grid member positioned in said pot above some of said air holes and below others of said holes and extending transversely of said pot, said grid being provided with apertures and shielding means overlying the same, said grid member comprising a plurality of vertically spaced overlapping and imperforate ring elements and an uppermost imperforate plate providing a plurality of annular passages for directing substantially all initially vaporized gases from therebeneath outwardly to the interior of the D thereabove, and means to supply oil-at the bottom of said pot.

4. An oil burner comprising a pot having a bottom and a side wall, such side wall bei provided with air holes at different levels, a grid member positioned in said pot above m of said air holes and below others of said holes and extending transversely of said pot, said grid being provided with apertures and shielding means overlying the same, said grid member comprising a plurality of vertically spaced overlapping vand imperforate ring elements and an uppermost imperforate plate providing passages for directing substantially all initially vaporized gases from therebeneath outwardly to the interior of the pot thereabove, said elements decreasing in diameter from the bottom element to the top element, and means to supply oil at the bottom of said pot.

5. An article of manufacture comprising a disc for installation in a pot type oil burner, said disc being of peripheral contour such as to fit within the side wall of such a burner in substantially peripheral engagement therewith and having portions thereof bent or struck up to provide passages inclined upwardly and radially toward the outer periphery of said disc.

6. An article of manufacture comprising a disc for installation in a pot type oil burner, said disc being of peripheral contour such as to fit within the side wall of such a burner in substantially peripheral engagement therewith and having portions thereof bent or struck up to provide apertures therethrough inclined upwardly and radially toward the outer periphery of said disc, said bent-up portions overlying said apertures formed therebeneath.

7. In a liquid fuel pot type burner characterized by means forming a lower fuel vaporizing chamber, including side walls having air inlet holes and an imperforate bottom, means forming an upper aeration chamber, including side walls having air inlet holes, an improved grid member separating said upper and lower chambers, and fuel supply means connected to said lower chamber; means forming said grid, comprising plate means defining a. plurality of apertures interconnecting said chambers,- and imperforate shielding means. overlying'said apertures to insure shielding of the lower chamber from the radiant heat of the resulting flame front and to effect directing of substantially all of the initially vaporized gases from said lower chamber upwardly into said upper chamber and outwardly only toward said side Walls.

' WILLIAM O. HORNE.

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